Noninvasive detection of allograft rejection in heart transplant recipients by use of Doppler tissue imaging

Abstract

Background: Allograft rejection in heart transplant recipients is associated with lymphocytic extracellular infiltration and edema resulting in increased myocardial stiffness and abnormal relaxation. We hypothesize that these abnormalities will result in reduced myocardial relaxation velocities. Doppler tissue imaging is a novel noninvasive imaging modality that is capable of quantifying myocardial tissue velocities and may therefore be useful to identify allograft rejection.

Methods: In this observational study, 121 heart transplant recipients underwent pulsed-wave Doppler tissue imaging at the time of their surveillance endomyocardial biopsies. Peak relaxation and systolic velocities were measured from the inferior wall blinded to clinical biopsy. Biopsy results were classified as rejecting (3a, 3b, 4) or nonrejecting (0, 1a, 1b).

Results: The peak relaxation velocity in nonrejecting allograft recipients (n = 98) was 0.21 m/sec +/- 0.01. During moderate allograft rejection (n = 16), peak relaxation velocities decreased to 0.14 m/sec +/- 0.01 (p < 0.0001), and subsequently increased to 0.23 m/sec +/- 0.0 after successful treatment (p = 0.0001). Peak systolic velocities did not change during rejection, 0.08 m/sec +/- 0.02 when compared with nonrejecting recipients 0.09 +/- 0.02 (p = NS). With a cutoff value of less than 0.16 m/sec, the sensitivity of peak myocardial relaxation velocities for detection of rejection was 76%. The specificity and negative predictive values were 88% and 92%, respectively.

Conclusion: Moderate allograft rejection results in reduced myocardial relaxation velocities, which can be detected noninvasively with pulsed-wave Doppler tissue imaging. Hence, Doppler tissue imaging is a useful noninvasive tool to exclude allograft rejection.